A heavy water reactor waste filter element deuterium removal and dehumidification experimental device and method

Abstract

The present invention relates to a device and method for conducting a detritium and dehumidification experiment on a waste filter element of a heavy water reactor. The device comprises: a sealed oven for simulating a tritium precipitation environment of a waste filter element and accommodating a filter element to be tested; a circulating air module for establishing a closed gas circulation system and carrying precipitated moisture, comprising a variable frequency blower and an air inlet and outlet duct system; a tritium water adsorption and purification module for simulating the adsorption and purification process of tritium water, comprising at least one molecular sieve adsorption tank that can be connected in series; an automated control module for regulating experimental process parameters and recording experimental data, the automated control module being capable of controlling at least the operating parameters of the variable frequency blower and the temperature of the sealed oven, and monitoring and recording system operating data in real time; the circulating air module, the tritium water adsorption and purification module and the automated control module being integrated into an integrated equipment body, the integrated equipment body being sealedly connected to the sealed oven via the air inlet and outlet duct system, and being capable of maintaining sealing performance under an operating pressure of 0.5±0.1 kPa.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of radioactive waste management, and particularly relates to a heavy water reactor waste filter cartridge deuterium removal and dehumidification experimental device and method. BACKGROUND

[0002] During the operation of a nuclear power plant, a water filter is an important equipment in a nuclear island radioactive water treatment system. The filter is mainly applied in two aspects: one is to filter impurities such as suspended solids in the water process of a reactor primary loop and related systems, to ensure the stable operation of the unit and related systems; and the other is to reduce the radioactivity and chemical composition content of waste liquid in the drainage process of the primary loop blowdown system, waste liquid treatment system and the like, to ensure that the discharged waste liquid can meet the requirements of local environmental protection policies.

[0003] The filter cartridge of the water filter needs to be replaced regularly, and the replacement time is usually based on two conditions: the expiration of a predetermined replacement period or the pressure difference reaching a set value. When the contact dose rate of the discarded filter cartridge (referred to as “waste filter cartridge”) exceeds the safety limit value, the waste filter cartridge needs to be loaded into a special shielding container and then transported to a waste storage library for storage. In the storage library, the waste filter cartridge is stored in a vertical manner in a concrete container underground, and a top cover is installed on the top of the container to realize sealed storage.

[0004] However, the above-mentioned storage method has several outstanding problems: first, the stored waste filter cartridge has a high dose rate and contains a large amount of tritium water, so workers cannot directly contact and handle it; second, any operation that needs to handle the waste filter cartridge must open the top cover of the concrete container to remove the waste filter cartridge, which inevitably causes tritium water to overflow, causing radiation hazards to the environment and personnel; in addition, since the number of concrete containers in the storage library is limited, and the waste filter cartridges generated by operation continue to increase, the storage library is facing capacity pressure. SUMMARY

[0005] The present application discloses a heavy water reactor waste filter cartridge deuterium removal and dehumidification experimental device and method, which aims to solve the technical problems existing in the prior art.

[0006] The present application adopts the following technical solutions:

[0007] On the one hand, the present application provides a heavy water reactor waste filter cartridge deuterium removal and dehumidification experimental device, which comprises:

[0008] a sealed oven for simulating the tritium outgassing environment of the waste filter cartridge and accommodating the filter cartridge to be experimented;

[0009] a circulating air module for establishing a closed gas circulation system and carrying outgassed moisture, the circulating air module comprising a variable frequency fan for generating adjustable air flow and an air inlet and outlet pipeline system for air flow delivery;

[0010] a tritium water adsorption purification module for simulating the adsorption purification process of tritium water, the tritium water adsorption purification module comprising at least one molecular sieve adsorption tank connectable in series, the molecular sieve adsorption tank being used to verify the adsorption effect of the molecular sieve on moisture;

[0011] an automatic control module for regulating experimental process parameters and recording experimental data, the automatic control module being capable of at least controlling the operating parameters of the variable frequency fan and the temperature of the sealed oven, and monitoring and recording system operating data in real time;

[0012] The circulating air module, the tritium water adsorption purification module and the automatic control module are integrated into an integrated equipment main body, the integrated equipment main body is sealingly connected with the sealed oven through the air inlet and outlet pipeline system, and can maintain sealing at an operating pressure of 0.5±0.1 kPa.

[0013] As a preferred technical solution, the sealed oven comprises an oven body and a temperature adjusting unit.

[0014] The oven body is provided with an air inlet end and an air outlet end for air circulation, the air inlet end and the air outlet end are sealingly connected with the air inlet and outlet pipeline system respectively, the air inlet end is provided with a hygrometer for monitoring the air inlet parameters, and the air outlet end is provided with a hygrometer for monitoring the air outlet parameters, a flow meter for measuring the gas flow and a water vapor separator for gas-liquid separation.

[0015] The temperature adjusting unit is used to simulate the water analysis out process under different temperature conditions.

[0016] As a preferred technical solution, the circulating air module comprises a variable frequency fan, an air inlet pipeline, an air outlet pipeline, a main pipeline and an air speed meter.

[0017] The variable frequency fan is used to simulate different circulating air conditions, and the output flow of the variable frequency fan can be adjusted at least in the range of 5-15 m 3 / h to meet different experimental conditions;

[0018] The air inlet pipeline is sealingly connected with the air inlet end of the sealed oven, and the air outlet pipeline is sealingly connected with the air outlet end of the sealed oven, the air inlet pipeline and the air outlet pipeline both adopt a detachable sealing connection structure; the main air pipeline is used to connect the air inlet pipeline and the air outlet pipeline.

[0019] The air speed meter is arranged on the air inlet pipeline and used to monitor the air inlet speed.

[0020] As a preferred technical solution, the tritium water adsorption purification module is arranged between the air outlet end of the sealed oven and the circulating air module, the tritium water adsorption purification module further comprises a desiccant tank, a plurality of molecular sieve adsorption tanks connectable in series are arranged in the desiccant tank, each molecular sieve adsorption tank is redundantly filled with molecular sieve, and adjacent molecular sieve adsorption tanks are sealingly connected through pipelines.

[0021] As a preferred technical scheme, in the plurality of series-connected molecular sieve adsorption tanks, the gas tritium absorption rate of the second last molecular sieve adsorption tank is greater than 95%, and the tritium water absorption rate of the last molecular sieve adsorption tank is 100%.

[0022] As a preferred technical scheme, the automatic control module comprises:

[0023] a control unit for controlling experimental operating parameters, including the opening and speed adjustment of the variable frequency fan, and the opening and temperature adjustment of the temperature adjustment unit;

[0024] a display unit for displaying the gas flow rate, temperature, pressure and temperature and humidity in the air inlet and outlet pipeline system in real time during the experiment;

[0025] a recording unit for automatically recording experimental process parameters.

[0026] In a second aspect, the embodiments of the present application provide a heavy water reactor waste filter core tritium removal and dehumidification experimental method realized by using the device of any one of the preceding aspects, comprising the following steps:

[0027] The water absorption of the filter core to be tested is determined, and the molecular sieve is loaded according to the water absorption;

[0028] The device running detection and sealing detection are performed;

[0029] The sealing oven temperature is adjusted, and the filter core is placed in the sealing oven;

[0030] The variable frequency fan is started to establish internal circulation airflow;

[0031] The inlet and outlet temperature and humidity are monitored, and when the outlet humidity is lower than the inlet and ambient humidity and maintains stable for 1h, it is determined that the tritium removal is completed;

[0032] The outlet temperature and humidity are used to determine the replacement time of the molecular sieve.

[0033] As a preferred technical scheme, in the step of determining the water absorption of the waste filter core and loading the molecular sieve, the step comprises:

[0034] The water absorption weight of the filter core to be tested is determined;

[0035] The required amount of molecular sieve is calculated according to the molecular sieve water absorption ratio of 0.2;

[0036] The molecular sieve with a saturated water absorption of 120% is loaded into the molecular sieve adsorption tank.

[0037] As a preferred technical scheme, before the step of performing device running detection and sealing detection, the step of establishing internal circulation of the device is further included.

[0038] In the device operation detection and sealing detection steps, the device operation detection includes stable operation of not less than 2h after the inner circulation is established, checking the operation state of the fan and the sealing oven, and detecting the signal display of the flow meter and the temperature and humidity meter;

[0039] The qualified standard of the sealing detection is that after the inner circulation is established, continuous operation is performed for 2h under the pressure of 0.5kPa, the pressure is maintained constant under different fan frequencies, and the pressure change rate is less than 5%.

[0040] As a preferred technical solution, when the temperature and humidity at the outlet of the last-stage molecular sieve tank are greater than 3%RH, it is determined that the molecular sieve has penetrated;

[0041] When the temperature and humidity are greater than the ambient humidity, it is determined that the molecular sieve has been completely saturated and needs to be replaced.

[0042] The technical solution adopted by the present application can achieve the following beneficial effects:

[0043] The present application mainly provides a heavy water reactor waste filter core deuterium removal and dehumidification experimental device and method, specifically, the experimental device provided by the present application embodiment adopts innovative modular design, integrates the circulating air module, the gas adsorption purification module and the automatic control module into an integrated structure, realizes stable sealing operation under the pressure of 0.5±0.1kPa through reliable sealing connection between the sealing oven and the equipment main body, and ensures the reliability of the experimental process.

[0044] Further, the present application embodiment designs a complete experimental parameter monitoring and control system, and the adjustable operating temperature (40-60℃) and the adjustable circulating air speed (5-15m 3 / h) can meet the needs of different experimental conditions; through real-time monitoring of temperature, humidity, flow and other key parameters, combined with automatic control and data recording function, the accuracy and repeatability of the experimental process are ensured. In addition, the present application embodiment also designs a series molecular sieve adsorption system and a performance verification method thereof, which can realize quantitative evaluation of the molecular sieve adsorption effect, and provides an important basis for optimizing the design of the engineering device.

[0045] Based on the above device, the present application embodiment also provides a specific experimental method based on the above experimental device, in which water is used instead of tritiated water for experimental operation, avoiding the use of radioactive substances, ensuring the safety of the experiment, and greatly reducing the research cost, through systematic operation in the laboratory environment, providing reliable experimental data and technical support for the subsequent development of the engineering deuterium removal device. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced as follows, which form a part of the present application. The illustrative embodiments of the present application and the description and explanation thereof do not constitute an improper limitation to the present application. In the drawings:

[0047] Figure 1 A structure schematic diagram of a heavy water reactor waste filter core deuterium removal and dehumidification experimental device in an embodiment of the present application;

[0048] Figure 2 A flow schematic diagram of a heavy water reactor waste filter core deuterium removal and dehumidification experimental method in an embodiment of the present application;

[0049] Figure 3 A 40℃, 5m 3 / h flow rate long-term operation molecular sieve adsorption capacity determination experimental result diagram in an embodiment of the present application;

[0050] Figure 4 A 50℃, 5m 3 / h flow rate long-term operation experimental result diagram of the device in an embodiment of the present application;

[0051] Figure 5 A 50℃, 10m 3 / h flow rate long-term operation experimental result of the device in an embodiment of the present application.

[0052] Explanation of the reference signs:

[0053] Sealing oven 11, frequency conversion fan 12, air inlet pipeline 13, air outlet pipeline 14, desiccant tank 15, temperature and humidity meter 16, flow meter 17. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be described clearly and completely in combination with the specific embodiments of the present application and the corresponding drawings. In the description of the present application, it should be noted that the term “or” is generally used in the meaning of including “and / or”, unless the content is explicitly indicated otherwise.

[0055] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected, it can be mechanical connection, or magnetic connection, it can be directly connected, or indirectly connected through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. In addition, in the description of the present application, the terms "first", "second" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the specific embodiments of the specification, "oven" means "sealed oven", "fan" means "variable frequency fan", and "device" means "heavy water reactor waste filter core tritium removal and dehumidification experimental device".

[0056] At present, the research on the tritium removal technology of heavy water reactor waste filter core mainly depends on the direct use of radioactive substances, and the waste filter core is temporarily stored in a concrete container. Any processing or research on it needs to open the top cover of the concrete container and remove the waste filter core, and then the relevant tritium removal and dehumidification treatment or related experiments can be carried out. This not only increases the cost of research, but also brings potential harm to experimental personnel and environment due to tritium water overflow.

[0057] Tritium in the waste filter core is mainly in the form of tritiated water remaining in the waste filter core. Water and tritiated water have the same physical and chemical properties. To solve the problems existing in the prior art, the embodiments of the present application provide a heavy water reactor waste filter core tritium removal and dehumidification experimental device. The device uses water instead of tritiated water to carry out tritium removal and / or dehumidification experiments, which can avoid using radioactive tritium for research, significantly save operating costs, reduce radiation risks, and also improve the safety of experimental site radiation, personnel and environment.

[0058] Reference Figure 1 The heavy water reactor waste filter core tritium removal and dehumidification experimental device comprises a sealed oven 11, a circulating air module, a tritium water adsorption and purification module, and an automatic control module. The circulating air module, the tritium water adsorption and purification module, and the automatic control module can be integrated into a device main body. The device main body is sealingly connected to the sealed oven 11 through an air inlet and outlet pipeline system to form a sealed circulating system, and can maintain the sealing property under an operating pressure of 0.5±0.1kPa.

[0059] Specifically, the sealed oven 11 is used to simulate the tritium outgassing environment of the waste filter element and accommodate the filter element to be tested; the circulating air module is used to establish a closed gas circulation system and carry out the outgassing moisture, and the circulating air module comprises a variable frequency fan 12 and an air inlet and outlet pipeline system, wherein the variable frequency fan 12 is used to generate adjustable air flow, and the air inlet and outlet pipeline system is used for air flow delivery; the tritiated water adsorption and purification module is used to simulate the adsorption and purification process of tritiated water, and the tritiated water adsorption and purification module comprises at least one molecular sieve adsorption tank which can be connected in series, and the molecular sieve adsorption tank is used to verify the adsorption effect of the molecular sieve on moisture; the automatic control module is used to regulate the experimental process parameters and record the experimental data, and the automatic control module can at least control the operating parameters of the variable frequency fan 12 and the temperature of the sealed oven 11, and monitor and record the system operating data in real time.

[0060] In a preferred embodiment, the sealed oven 11 comprises an oven body and a temperature adjusting unit, wherein the oven body is provided with an air inlet end and an air outlet end, the air inlet end and the air outlet end are respectively sealedly connected with the air inlet and outlet pipeline system, the air inlet end is provided with a hygrometer 16 for monitoring the air inlet parameters, the air outlet end is provided with a hygrometer 16 for monitoring the air outlet parameters, a flow meter 17 for measuring the gas flow, and a gas-water separator for gas-liquid separation; the temperature adjusting unit is used to simulate the water outgassing process under different temperature conditions.

[0061] Preferably, the oven body is made of 304 stainless steel, which has good corrosion resistance and sealing performance; since there is a test demand for filter elements of different sizes, the volume of the oven body is not specifically limited in this embodiment, and those skilled in the art can make corresponding selection and adjustment according to actual needs.

[0062] Preferably, the air inlet end and the air outlet end are respectively used for the inflow and outflow of the gas, and the reliable connection with the air inlet and outlet pipeline system can be achieved through the connection mode of standard flanges. In order to ensure the sealing performance, rubber gaskets can be arranged at the flange connection positions for sealing.

[0063] Preferably, the hygrometer 16 of the air inlet end is used to monitor the gas temperature and humidity parameters entering the oven body in real time, the hygrometer 16 of the air outlet end is used to monitor the temperature and humidity changes of the outlet gas, the gas flow meter 17 is used to measure the circulating gas flow, and the gas-water separator is used to collect the outgassed liquid water to prevent moisture from entering the subsequent pipeline.

[0064] In a preferred embodiment, the temperature adjusting unit comprises a heater, a temperature sensor and a temperature controller. The heater can control the oven body temperature in the range of 40-60℃, and the temperature fluctuation range is controlled within ±1℃; the temperature sensor is used to monitor the internal temperature of the oven body in real time; the temperature controller can automatically adjust the heater power according to the set temperature to ensure that the oven body temperature is stable and controllable. In this embodiment, the specific configuration of the heater, the temperature sensor and the temperature controller is not limited.

[0065] In a preferred embodiment, the circulating air module is the core component for realizing directional circulation of gas, and is used to provide stable airflow conditions for the dehumidification process of the waste filter element. Its structure includes at least a variable frequency fan 12, an air inlet pipe 13, an air outlet pipe 14, a main pipe and an anemometer.

[0066] Preferably, the variable frequency fan 12 is used to simulate different circulating airflow conditions, and the output flow of the variable frequency fan 12 can be at least 5-15m 3 / h range to meet different experimental conditions; the air inlet duct 13 is sealed with the air inlet end of the sealed oven 11, and the air outlet duct 14 is sealed with the air outlet end of the sealed oven 11, and both the air inlet duct 13 and the air outlet duct 14 adopt a detachable sealed connection structure; the main air duct is used to connect the air inlet duct and the air outlet duct; the anemometer is set on the air inlet duct 13 to monitor the air inlet speed.

[0067] In a preferred embodiment, the tritium water adsorption purification module is arranged between the air outlet end of the sealed oven 11 and the circulating air module. The tritium water adsorption purification module also includes a desiccant tank 15. A partition plate is provided inside the tank body to form a plurality of independent molecular sieve adsorption tank chambers. A plurality of molecular sieve adsorption tanks that can be connected in series are arranged in the desiccant tank 15. Each molecular sieve adsorption tank is redundantly filled with molecular sieves, and adjacent molecular sieve adsorption tanks are sealed and connected by pipelines.

[0068] Preferably, among multiple molecular sieve adsorption tanks connected in series, the gas tritium absorption rate of the penultimate molecular sieve adsorption tank is greater than 95%, and the tritium water adsorption rate of the last molecular sieve adsorption tank is 100%. Taking four molecular sieve adsorption tanks connected in series as an example, the first two molecular sieves are mainly used for preliminary adsorption and reduction of tritium concentration, the gas tritium absorption rate of the third molecular sieve adsorption tank is greater than 95%, and the tritium water adsorption rate of the fourth molecular sieve adsorption tank is 100%, so as to adsorb all the remaining tritium and ensure that the tritium content in the outlet gas is reduced to the background level. It should be noted that the number of molecular sieve adsorption tanks in the series structure can be increased or decreased as needed and is not necessarily limited to four. For example, when the tritium concentration is low, only two adsorption tanks can be used for treatment, which can both meet the treatment requirements and reduce the system resistance; when treating high-concentration tritium, more adsorption tanks are set to ensure the treatment effect.

[0069] Preferably, in order to monitor the adsorption effect of each level of molecular sieve, a temperature and humidity sensor is set at the inlet and outlet of each level of adsorption tank. When the humidity at the outlet of a certain level of molecular sieve exceeds 3% RH, it indicates that the molecular sieve of this level is close to saturation and needs to be regenerated or replaced.

[0070] In a preferred embodiment, the automation control module takes a programmable logic controller (PLC) as the core, and its functional units include a control unit, a display unit and a recording unit, wherein the control unit is used to control experimental operating parameters, including the opening and speed adjustment of the variable frequency fan 12, and the opening and temperature adjustment of the temperature adjustment unit; the display unit is used to display the gas flow rate, temperature, pressure and temperature and humidity in the air inlet and outlet pipeline system in real time during the experiment; and the recording unit is used to automatically record experimental process parameters, including running time, gas flow, temperature, pressure and other data, which can be used for operation analysis and optimization, and can also serve as an important basis for quality traceability.

[0071] Through the organic combination of the above functional units, the automation control module realizes accurate control, real-time display and reliable recording of system operating parameters, thereby providing a strong guarantee for the automatic operation of the experimental process and data analysis.

[0072] For example, Figure 2 In another embodiment of the present application, a heavy water reactor waste filter element deuterium removal and dehumidification experiment method is also provided, which is operated based on the heavy water reactor waste filter element deuterium removal and dehumidification experiment device described above, and preferably, the experiment method at least includes the following steps:

[0073] The water absorption of the filter element to be tested is determined, and the molecular sieve is loaded according to the water absorption;

[0074] The device operation detection and sealing detection are performed;

[0075] The sealing oven temperature is adjusted, and the filter element is placed in the sealing oven;

[0076] The variable frequency fan is started to establish internal circulation airflow;

[0077] The inlet and outlet temperature and humidity are monitored, and when the outlet humidity is lower than the inlet and ambient humidity and maintains stable for 1 h, it is determined that the deuterium removal is completed;

[0078] The outlet temperature and humidity are used to determine the replacement time of the molecular sieve.

[0079] Preferably, when the molecular sieve is loaded, the filter element is first drained and weighed (M1), and the water absorption weight M1-M0 is obtained, wherein M0 is the weight of the dry filter element; then the required amount of molecular sieve for saturated water absorption is calculated according to the obtained water absorption, and preferably, the required amount of molecular sieve is calculated according to the molecular sieve water absorption ratio of 0.2; then 120% of the saturated water absorption of the molecular sieve is loaded into the molecular sieve adsorption tank, and after the loading is completed, each tank is closed and connected with the main pipeline.

[0080] Preferably, before the device operation detection and sealing detection steps, the device needs to be started first, and the internal circulation is established by the variable frequency fan.

[0081] Preferably, in the device operation detection and sealing detection steps, the device operation detection includes stable operation for not less than 2 hours after the internal circulation is established, the operation state of the fan and the sealing oven is checked, and the signal display of the flow meter and the temperature and humidity meter is detected; when each component and equipment of the device can be stably operated for not less than 2 hours, the device operation detection is completed.

[0082] Preferably, the qualified standard of the sealing detection is that, after the internal circulation is established, the device is continuously operated for 2 hours under a pressure of 0.5 kPa, and the pressure is maintained constant under different fan frequencies, the pressure is not higher than 0.5 kPa, and the pressure is maintained constant under different operating frequencies of the variable frequency fan, i.e. different flow rates, and the pressure variation rate is less than 5%.

[0083] Preferably, after the sealing detection is qualified, the oven is stopped (at room temperature) or preheated to a specified temperature (40℃, 50℃ and 60℃) in advance, and after the temperature is maintained stable for 1 hour, the filter core which has completed water absorption saturation and water draining is placed in the internal sealing oven.

[0084] Preferably, when the internal circulation is established, the fan frequency can be adjusted to establish the filter core deuterium removal / drying experiment under different flow rates (internal circulation flow rates of 5m 3 / h, 10m 3 / h and 15m 3 / h).

[0085] Preferably, when the outlet temperature and humidity of the last-stage molecular sieve tank are greater than 3% RH, it is determined that the molecular sieve has penetrated; when the outlet temperature and humidity are greater than the ambient humidity, it is determined that the molecular sieve has been completely saturated and needs to be replaced.

[0086] In order to verify the feasibility and effectiveness of the heavy water reactor waste filter core deuterium removal and drying experiment device provided in the above embodiments, in one specific embodiment of the present application, the following verification experiment is performed.

[0087] (1) Steam flow output experiment

[0088] The main purpose of this experiment is to study the time required for the waste filter core to reach the specified humidity index (the inlet humidity reaches 90% RH) under different working conditions (temperature and flow combination). Specifically, the steam flow generation rate of the filter core after water absorption saturation and water draining is taken as the reference index of the device inlet humidity, and the time required for the inlet humidity to reach 90% RH under different experimental conditions is shown in Table 1.

[0089]

[0090]

[0091] Table 1 Saturation water absorption, water release filter core vapor flow rate of production

[0092] From the data of the above experiment, the higher the temperature, the shorter the time required to reach the target humidity; at the same temperature, the greater the flow, the shorter the time to reach the target humidity; when the temperature reaches 50°C or above, the effect of continuing to increase the temperature on the time is no longer significant. The results of this experiment provide an important basis for determining the optimal combination of process parameters, which can help to select operating conditions that can ensure dehumidification effect and economic efficiency.

[0093] (2) Molecular sieve adsorption capacity determination experiment

[0094] Preferably, at 40°C, 5m 3 / h molecular sieve breakthrough adsorption experiment.

[0095] The experiment uses two small molecular sieve adsorption tanks (01 and 02), each tank contains 1.8 kg of molecular sieve, which are connected to the device separately for dehumidification. The molecular sieve in tank 01 is replaced immediately after being saturated with moisture, and the filter core contains more water than the saturated water absorption of the molecular sieve used in tanks 01 and 02.

[0096] After the device dehumidification is completed, the water-saturated filter core is placed in a 40°C oven at 9:25, and the flow rate is controlled at 5m 3 / h. First use tank 01, then replace tank 02 after saturation. The long-term changes in inlet and outlet temperature and humidity over time during the entire experiment process are shown in Figure 3 . After the operation is completed, the outlet humidity data analysis shows that the outlet humidity decreases to the minimum value of 3% RH at 9:52, and maintains until 11:58, after which the humidity starts to grow rapidly, and the inlet and outlet humidity increases to 89.4% RH / 73.3% RH at 18:36. At 18:40, replace tank 02, and at 23:20, the outlet humidity reaches 3.8% RH and increases rapidly. The next day at 7:00, the operation is completed, and the inlet and outlet humidity is 84.7% RH / 72.7% RH.

[0097] Through data analysis, when tank 01 is connected and operated, the outlet humidity decreases to the minimum value of 2.7% RH at 11:14 and maintains until 11:36, after which it starts to grow, and it is considered that the molecular sieve has been penetrated at this time. The humidity slowly increases to 3.9% RH at 12:30, and it is preliminarily determined that the molecular sieve penetration rate in the time period from 11:36 to 12:30 is acceptable. Figure 3 Through data analysis, when tank 01 is connected and operated, the outlet humidity decreases to the minimum value of 2.7% RH at 11:14 and maintains until 11:36, after which it starts to grow, and it is considered that the molecular sieve has been penetrated at this time. The humidity slowly increases to 3.9% RH at 12:30, and it is preliminarily determined that the molecular sieve penetration rate in the time period from 11:36 to 12:30 is acceptable.

[0098] 02 tank connected, run to 20:15 out of the gas humidity decreased to the minimum value of 1.8 kg / kg and maintained to 21:14, then slowly grow to 23:20 reached 3.8% RH, then the speed of growth is faster, then consider 21:14 after 02 molecular sieve tank molecular sieve has been penetrated, data analysis to penetrate the water absorption of about 0.056 kg / kg, acceptable molecular sieve penetration water absorption range of about 100 ~ 209 g (0.056 ~ 0.116 kg / kg, humidity of 3.8% RH, 3% RH limit the value is large); run the end of the molecular sieve water absorption of 0.23 kg / kg.

[0099] The experimental operation conditions, molecular sieve penetration water absorption of about 0.056 kg / kg, acceptable penetration water absorption range of about 0.056 ~ 0.116 kg / kg, saturated water absorption of 0.23 kg / kg.

[0100] (3) long-term filter core dehumidification experiment

[0101] a) temperature 50℃, 5m 3 / h flow

[0102] Laboratory temperature 24℃, initial air humidity 50.3% RH, temperature 24.3℃; air humidity 53.2% RH, temperature 24℃. After dehumidification 9:44 into the filter core to start the test, run to 11:45, fan outlet temperature 30.8℃ or so, the middle temperature 27.6℃ or so, the tail (oven connection pipe connection) temperature 24.6℃; molecular sieve tank inlet temperature 26.4℃, air outlet temperature 30.6℃, fan inlet temperature 25.4℃ or so. Run to 15:25, fan outlet temperature 31.8℃ or so, the middle temperature 28.1℃ or so, the tail temperature 26.2℃; molecular sieve tank inlet temperature 26.3℃, air outlet temperature 40.0℃, fan inlet temperature 27.9℃ or so.

[0103] Water saturated filter core placed in a 50℃ oven, the device runs to maintain 5m 3 / h flow, inlet / outlet temperature and humidity changes over time is shown in Figure 4 .

[0104] The device starts to run 1# small molecular sieve tank and 1# large molecular sieve tank connected to use, respectively, 1.8 kg and 3.7 kg of molecular sieve, wherein 1# small molecular sieve tank is connected with the inlet (1# large molecular sieve tank is connected with the outlet), the filter core water weight is 3136.5g.

[0105] The device was dehumidified for 5 minutes at 9:44 am, and the water filter was placed in the water filter. The inlet and outlet humidity was 14.7% RH / 10.9% RH. The humidity reached a maximum of 94.1% RH at 10:15, and then gradually decreased to a minimum of 7.4% RH at 8:30 the next day. The humidity reached a maximum of 88.9% RH at 10:05, and then gradually decreased to 2% RH at 10:42, and then slowly decreased to a minimum of 0.6% RH at 20:57 and maintained until 23:21. The humidity changed slowly during the entire dehumidification process, and the humidity increased to a maximum of 1.9% RH at the end of the operation. After the device was operated for about 23 hours, the inlet and outlet humidity reached 7.4% RH / 1.9% RH, and the change trend was slow. The inlet humidity showed a downward trend and was lower than 8% RH; indicating that the water content in the filter was very low at this time, and the water vapor generation rate was very low, and the molecular sieve tank had no obvious heat release, indicating that the molecular sieve had less heat release due to less water absorption and was close to saturation. The device was turned off, and the filter was removed and weighed. There was no water vapor feeling when the oven door was opened (indicating that the water vapor generation rate of the filter was very low at this time).

[0106] The outlet humidity changed slowly during the entire operation process, and increased to 1.9% RH at 10:42. The operation mode showed that the filter vapor rate was low and flat, and the small amount of water vapor produced could be fully absorbed by the molecular sieve. The molecular sieve was not penetrated or only a small amount of water vapor penetrated the molecular sieve, so that the outlet humidity remained at a very low level. This mode is a safer mode from the perspective of molecular sieve penetration during operation, but the operation time is longer.

[0107] After the experiment was completed, it was found by weighing that 1.8 kg of molecular sieve in the 1# small molecular sieve tank absorbed 429 g of water, with a water absorption rate of 0.238 kg / kg, which was slightly higher than the water absorption amount of the molecular sieve used in the experiment; 3.7 kg of molecular sieve in the 1# large molecular sieve tank absorbed 0.66 kg of water, with a water absorption rate of 0.178 kg / kg, which was close to the water absorption amount of the molecular sieve used in the experiment. The molecular sieve absorbed 1089 g of water. The initial weight of the filter was 3136.5 g, and the weight after the dehumidification experiment was completed was 2051.7 g, a total of 1085 g of water was removed, and the amount of water absorbed by the molecular sieve was close to the amount of water evaporated by the filter.

[0108] b) temperature 50℃, 10 m 3 / h flow rate

[0109] Lab temperature 24°C, initial inlet air humidity 50.3% RH, temperature 24.3°C; outlet air humidity 53.2% RH, temperature 24°C. After 9:44, the filter core was inserted to start the test, and the test was run until 11:21. The fan outlet temperature was about 46.4°C, the middle section temperature was about 32.7°C, and the tail end (oven connection pipe connection) temperature was 33.2°C. The molecular sieve tank inlet temperature was 23.2°C, the outlet temperature was 44.2°C, and the fan inlet temperature was about 31°C. The test was run until 15:05. The fan outlet temperature was about 37.2°C, the middle section temperature was about 34.1°C, and the tail end temperature was 30.2°C. The molecular sieve tank inlet temperature was 27.8°C, the outlet temperature was 37.2°C, and the fan inlet temperature was about 30.3°C.

[0110] The water-saturated and water-leaching filter core was inserted into a 50°C oven, and the device was run for 10 minutes at a flow rate of 10 m 3 / h. The long-term changes in the inlet and outlet temperature and humidity over time are shown in FIG. 1. Figure 5

[0111] The device was initially run with the 2# small molecular sieve tank connected to the inlet (the 2# large molecular sieve tank was connected to the outlet). The 2# small molecular sieve tank and the 2# large molecular sieve tank each contained 1.8 kg and 3.7 kg of molecular sieve, respectively. The weight of the water-leaching filter core was 3039.3 g.

[0112] The device was run for 5 minutes at 9:11 am, and the water-leaching filter core was inserted to start the dehumidification test. The initial humidity of the inlet and outlet was 16% RH / 7.2% RH, respectively. The humidity gradually decreased after the inlet humidity reached a maximum value of 94.7% RH at 9:23. The humidity decreased to a minimum value of 18.4% RH at 9:33. The outlet humidity reached a maximum value of 82.9% RH at 9:21, and then decreased to 2% RH at 9:39. The humidity slowly decreased to a minimum value of 0.5% RH at 10:58 and remained unchanged until 12:43. The humidity changed slowly during the entire dehumidification process. The humidity increased to a maximum value of 5.7% RH at the end of the test. The humidity of the inlet and outlet reached 18.4% RH / 5.7% RH, respectively, after the device was run for about 12 hours and 20 minutes. The humidity of the inlet showed a downward trend and was lower than 19% RH. This indicated that the water content in the filter core in the oven was very low, and the water vapor generation rate was also very low. At the same time, the molecular sieve tank did not release heat significantly, indicating that the molecular sieve released less heat due to the low water absorption and was close to saturation. The device was turned off, and the filter core was removed and weighed. No water vapor was felt when the oven door was opened (indicating that the water vapor generation rate of the filter core was very low at this time).

[0113] ​During the entire operation, the humidity at the air outlet changes slowly, dropping to 2% RH at 9:39, breaking through 3% RH at 15:34, and then slowly increasing to 5.7% RH at the end of the operation. This indicates that in this operation mode, the vapor rate of the filter element is low and gentle. After running to 15:34 (the humidity at the air outlet breaks through 3% RH), a small amount of water vapor penetrates the molecular sieve, and the humidity at the air inlet has been showing a slow downward trend. The surface molecular sieve always has the ability to absorb water and is not saturated. Compared with 5m 3 / h flow rate for long-term experiments. In this mode, the molecular sieve is penetrated but the amount of water penetrating is small and controllable, and the operation time is short. On-site operation can achieve safe detritium removal by connecting multiple molecular sieve tanks in series or regularly adjusting and reducing the operating flow rate.

[0114] After the experiment was completed, weighing revealed that the 1.8kg of molecular sieve in the 2# small molecular sieve tank absorbed 424g of water, with a water absorption rate of 0.236kg / kg, slightly higher than the water absorption of the molecular sieve used in the experiment. The 3.3kg of molecular sieve in the 2# large molecular sieve tank absorbed 0.5kg of water, with a water absorption rate of 0.151kg / kg, close to the water absorption of the molecular sieve used in the experiment. The molecular sieve absorbed 924g of water. The filter element had a starting weight of 3039.3g, and after the dehumidification experiment was completed, it weighed 2124.4g, removing a total of 915g of water. The water absorption of the molecular sieve is close to the amount of water evaporated from the filter element.

[0115] The long-term operation of laboratory experimental devices and a large number of molecular sieve dehumidification experimental studies have provided a large amount of basic data and operating experience for the design and operation of on-site thermal test experimental devices, including:

[0116] The 13X molecular sieve selected for the experiment and the 13X molecular sieve provided by the nuclear power site can effectively dehumidify when the engineering equipment is in operation, and can be used to remove tritium in on-site hot test experiments.

[0117] Under experimental operating conditions, the molecular sieve's water absorption capacity is approximately 0.056 kg / kg, with an acceptable range of approximately 0.056 to 0.116 kg / kg and a saturated water absorption capacity of 0.23 kg / kg. The saturated water absorption capacity of the molecular sieve can be determined to be 0.23 kg / kg, which is consistent with the water absorption capacity determined by the molecular sieve manufacturer. The water absorption capacity may be related to factors such as experimental conditions, molecular sieve tank size, and filling volume. The specific value of the on-site hot test experiment needs to be further determined based on the on-site hot test experiment.

[0118] The molecular sieve adsorption tank can effectively remove the tritium water carried out by the device through a multi-stage series circulation method. In the specific thermal test experiment, the multi-stage series molecular sieve adsorption tank can be used with molecular sieve redundancy to achieve safe adsorption of tritium.

[0119] Through different flow rate running test (5m 3 / h、10m 3 / h and 15m3 h) in actual operation, high flow rate operation should be matched with low flow rate to balance the tritium water absorption share in the series-connected molecular sieve absorption tank, so as to realize efficient and uniform absorption of tritium.

[0120] The oven is not in use, and the vapor rate of the filter core is lower than that in other heating operation modes. The small amount of water vapor generated can be fully absorbed by the molecular sieve, and the molecular sieve is not penetrated or only a small amount of water vapor penetrates the molecular sieve, so that the humidity at the outlet is always kept at a very low level. It can be determined that the tritium removal operation of the circulating air is the safest mode from the perspective of the penetration of the molecular sieve. (In actual operation, the time, cost, and appropriate amount of discharge reception should be considered. Based on the principle of radiation protection, it is not necessarily the lower the better, and it needs to be reasonable and feasible to be as low as possible.) During the actual hot test operation, the molecular sieve tank can be connected to the air inlet, or the oven can be turned on or hot air can be introduced to remove the accumulated water vapor. The specific operating parameters need to be determined through hot test experiments.

[0121] The small amount of water vapor generated under the condition of low flow rate of the circulating air can be fully absorbed by the molecular sieve, and the molecular sieve is not penetrated, so that the humidity at the outlet is always kept at a low level. This mode is the safest mode from the perspective of the penetration of the molecular sieve during operation, but the low water vapor generation efficiency of the filter core leads to a long time for on-site work and low tritium removal efficiency. It should be noted that the time, cost, and appropriate amount of discharge reception should be considered. Based on the principle of radiation protection, it is not necessarily the lower the better, and it needs to be reasonable and feasible to be as low as possible.

[0122] During long-term operation, a small amount of internal water vapor may accumulate. During the actual hot test operation, the molecular sieve tank can be connected to the air inlet, or the oven temperature can be intermittently increased, the hot air temperature can be increased, or the flow rate can be increased to remove the accumulated water vapor.

[0123] Laboratory experiments show that the measured humidity at the outlet reaches 3% RH, the water absorption rate of the molecular sieve is significantly reduced, the dehumidification efficiency of the device is decreased, and the penetration amount of the molecular sieve is increased. During the hot test experiment, the measured humidity at the outlet is taken as a reference, and the molecular sieve is replaced.

[0124] The embodiments of the application are described above in combination with the drawings, but the application is not limited to the specific embodiments described above. The specific embodiments described above are only illustrative, not limiting, and those skilled in the art can make many forms under the inspiration of the application without departing from the purpose of the application and the scope protected by the claims.

Claims

1. A heavy water reactor waste filter element detritium and dehumidification experimental device, characterized in that: include: -Sealed oven, used to simulate the tritium precipitation environment of spent filter elements and to accommodate the filter elements to be tested; - A circulating air module, used to establish a closed gas circulation system and carry away precipitated moisture. The circulating air module includes a variable frequency fan for generating an adjustable airflow and an inlet and outlet air duct system for airflow transportation; - A tritium water adsorption purification module, used to simulate the adsorption purification process of tritium water. The tritium water adsorption purification module includes at least one molecular sieve adsorption tank that can be connected in series. The molecular sieve adsorption tank is used to verify the adsorption effect of the molecular sieve on water; - an automated control module, used to adjust experimental process parameters and record experimental data. The automated control module can at least control the operating parameters of the variable frequency fan and the temperature of the sealed oven, and monitor and record system operating data in real time; Among them, the circulating air module, the tritium water adsorption purification module and the automation control module are integrated into an integrated equipment body, and the integrated equipment body is sealed with the sealed oven through the inlet and outlet air duct system and can maintain sealing under an operating pressure of 0.5±0.1kPa.

2. The heavy water reactor waste filter element tritium removal and dehumidification experimental device according to claim 1, characterized in that: The sealed oven includes a box body and a temperature regulating unit; The box body is provided with an air inlet end and an air outlet end for gas circulation, the air inlet end and the air outlet end are respectively sealedly connected to the air inlet and outlet pipe systems, the air inlet end is provided with a thermometer and hygrometer for monitoring air inlet parameters, and the air outlet end is provided with a thermometer and hygrometer for monitoring air outlet parameters, a flow meter for measuring gas flow, and a steam-water separator for gas-liquid separation; The temperature regulating unit is used to simulate the water separation process under different temperature conditions.

3. The heavy water reactor waste filter element tritium removal and dehumidification experimental device according to claim 2, characterized in that: The circulating air module includes the variable frequency fan, air inlet pipe, air outlet pipe, main pipe and anemometer; The variable frequency fan is used to simulate different circulating airflow conditions, and the output flow of the variable frequency fan can be adjusted within a range of at least 5-15m³ / h to meet different experimental conditions; The air inlet pipe is sealedly connected to the air inlet end of the sealed oven, and the air outlet pipe is sealedly connected to the air outlet end of the sealed oven. Both the air inlet pipe and the air outlet pipe adopt a detachable sealed connection structure; the main pipe is used to connect the air inlet pipe and the air outlet pipe; The anemometer is arranged on the air inlet duct to monitor the air inlet speed.

4. The heavy water reactor waste filter element tritium removal and dehumidification experimental device according to claim 2, characterized in that: The tritium water adsorption purification module is arranged between the air outlet end of the sealed oven and the circulating air module. The tritium water adsorption purification module also includes a desiccant tank. A plurality of molecular sieve adsorption tanks that can be connected in series are arranged in the desiccant tank. Each molecular sieve adsorption tank is redundantly filled with molecular sieves, and adjacent molecular sieve adsorption tanks are sealed and connected by pipelines.

5. The heavy water reactor waste filter element tritium removal and dehumidification experimental device according to claim 4, characterized in that: Among the multiple molecular sieve adsorption tanks connected in series, the gas tritium absorption rate of the penultimate molecular sieve adsorption tank is greater than 95%, and the tritium water adsorption rate of the last molecular sieve adsorption tank is 100%.

6. The heavy water reactor waste filter element tritium removal and dehumidification experimental device according to claim 2, characterized in that: The automation control module includes: - A control unit, used to control the experimental operating parameters, including the activation and speed adjustment of the variable frequency fan, and the activation and temperature adjustment of the temperature adjustment unit; - A display unit for displaying in real time the gas flow rate, temperature, pressure, and temperature and humidity in the air inlet and outlet pipe system during the experiment; -Recording unit, used to automatically record experimental process parameters.

7. An experimental method for removing tritium and dehumidifying a waste filter element of a heavy water reactor using the device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Determine the water absorption of the filter element to be tested and fill the molecular sieve according to the water absorption; Conduct device operation test and sealing test; Adjust the temperature of the sealed oven and place the filter element into the sealed oven; Start the variable frequency fan to establish internal circulation airflow; Monitor the inlet and outlet temperature and humidity. When the outlet humidity is lower than the inlet and ambient humidity and remains stable for 1 hour, the detritium removal is considered complete. Determine the timing of molecular sieve replacement based on outlet temperature and humidity.

8. The experimental method for removing tritium and dehumidification from a heavy water reactor waste filter element according to claim 7, characterized in that: The steps of measuring the water absorption of the filter element to be tested and filling the molecular sieve according to the water absorption include: Determine the water absorption weight of the filter element to be tested; Calculate the required amount of molecular sieve based on the molecular sieve water absorption ratio of 0.2; Place the molecular sieve with 120% saturated water absorption into the molecular sieve adsorption tank.

9. The experimental method for removing tritium and dehumidification from a heavy water reactor waste filter element according to claim 7, characterized in that: Before the steps of performing the device operation test and the sealing test, the method further includes the steps of: the device establishing an internal circulation; In the step of performing the device operation test and the sealing test, the device operation test includes stable operation for no less than 2 hours after the internal circulation is established, checking the operating status of the fan and the sealed oven, and testing the signal display of the flow meter and the thermometer and hygrometer; The qualified standard of the sealing test is: after the internal circulation is established, it runs continuously for 2 hours at a pressure of 0.5kPa, and the pressure is maintained constant at different fan frequencies, and the pressure change rate is less than 5%.

10. The experimental method for removing tritium and dehumidification from a heavy water reactor waste filter element according to claim 7, characterized in that: When the temperature and humidity at the outlet of the last stage molecular sieve tank is greater than 3%RH, it is determined that the molecular sieve has penetrated; When the humidity is greater than the ambient humidity, it is determined that the molecular sieve is completely saturated and needs to be replaced.

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